U.S. patent application number 15/266420 was filed with the patent office on 2017-03-16 for powder delivery for additive manufacturing.
The applicant listed for this patent is Hou T. Ng, Nag B. Patibandla, Raanan Zehavi. Invention is credited to Hou T. Ng, Nag B. Patibandla, Raanan Zehavi.
Application Number | 20170072636 15/266420 |
Document ID | / |
Family ID | 58257131 |
Filed Date | 2017-03-16 |
United States Patent
Application |
20170072636 |
Kind Code |
A1 |
Ng; Hou T. ; et al. |
March 16, 2017 |
POWDER DELIVERY FOR ADDITIVE MANUFACTURING
Abstract
An apparatus includes a platen and a dispensing system overlying
the platen. The dispensing system includes a powder source. The
dispensing system further includes a powder conveyor extending over
the top surface of the platen, rings arranged coaxially along a
longitudinal axis of the powder conveyor, and a cap plate extending
along a length of the tube. The powder conveyor is configured to
receive powder from the powder source. The powder conveyor is
configured to move the powder. The rings form a tube surrounding
the powder conveyor to contain the powder. Each concentric ring
includes a ring opening. Each ring is configured to be
independently rotatable. The cap plate includes a cap plate
opening. The powder is dispensed from the tube through the ring
opening and the cap plate opening when the ring opening and the cap
plate opening are aligned.
Inventors: |
Ng; Hou T.; (Campbell,
CA) ; Zehavi; Raanan; (Cupertino, CA) ;
Patibandla; Nag B.; (Pleasanton, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ng; Hou T.
Zehavi; Raanan
Patibandla; Nag B. |
Campbell
Cupertino
Pleasanton |
CA
CA
CA |
US
US
US |
|
|
Family ID: |
58257131 |
Appl. No.: |
15/266420 |
Filed: |
September 15, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62219605 |
Sep 16, 2015 |
|
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|
62262673 |
Dec 3, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22F 3/004 20130101;
B29C 64/205 20170801; B33Y 30/00 20141201; B22F 2999/00 20130101;
Y02P 10/25 20151101; B29C 64/20 20170801; B05C 19/04 20130101; B29C
64/153 20170801; B29C 31/02 20130101; B29C 64/241 20170801; B22F
3/1055 20130101; B29C 64/321 20170801; B22F 2999/00 20130101; B22F
2003/1056 20130101; B22F 3/004 20130101; B22F 2207/13 20130101;
B22F 2999/00 20130101; B22F 2003/1056 20130101; B22F 3/004
20130101; B22F 2207/01 20130101 |
International
Class: |
B29C 67/00 20060101
B29C067/00; B33Y 30/00 20060101 B33Y030/00 |
Claims
1. An additive manufacturing apparatus for forming an object, the
additive manufacturing apparatus comprising: a platen to support
the object being formed; a dispensing system overlying the platen,
the dispensing system comprising a powder source configured to hold
powder to be dispensed over a top surface of the platen, a powder
conveyor extending over the top surface of the platen, the powder
conveyor comprising a proximal end configured to receive the powder
from the powder source, the powder conveyor being configured to
move the powder carried within the powder conveyor along a length
of the powder conveyor, a plurality of rings arranged coaxially
along a longitudinal axis of the powder conveyor and forming a tube
surrounding the powder conveyor and configured to contain the
powder, and each concentric ring comprising at least one ring
opening; and a cap plate extending along a length of the tube, the
cap plate comprising at least one cap plate opening wherein each
ring is configured to be independently rotatable such that the at
least one ring opening of the respective concentric ring is movable
into or out of alignment with the at least one cap plate opening,
wherein the powder is dispensed from the tube through the at least
one ring opening and the at least one cap plate opening when the at
least one ring opening and the at least one cap plate opening are
aligned; and an energy source to apply energy to the powder
dispensed on the top surface of the platen to form a fused portion
of the powder.
2. The additive manufacturing apparatus of claim 1, wherein the
powder conveyor is rotatable about the longitudinal axis to move
the powder carried within the powder conveyor along the length of
the powder conveyor.
3. The additive manufacturing apparatus of claim 2, wherein the
powder conveyor further comprises a screw conveyor coaxial with the
longitudinal axis of the powder conveyor and rotatable about the
longitudinal axis of the powder conveyor such that, when the screw
conveyor rotates, the screw conveyor moves the powder carried
within the powder conveyor along the length of the powder
conveyor.
4. The additive manufacturing apparatus of claim 3, wherein: the
screw conveyor is configured such that when the screw conveyor
rotates in a first direction about the longitudinal axis, the screw
conveyor carries the powder along the longitudinal axis away from
the proximal end of the powder conveyor and when the screw conveyor
rotates in a second direction about the longitudinal axis, the
screw conveyor carries the powder along the longitudinal axis
toward the proximal end of the powder conveyor.
5. The additive manufacturing apparatus of claim 4, comprising a
motor to drive the screw conveyor and controller coupled to the
motor, wherein the controller is configured to cause the screw
conveyor to alternate between the rotation in the first direction
and the second direction during dispensing of the powder to form
the object.
6. The additive manufacturing apparatus of claim 4, wherein the
screw conveyor is configured to compact the powder when the screw
conveyor rotates in the first direction.
7. The additive manufacturing apparatus of claim 4, wherein the
controller is configured to cause the screw conveyor to, prior to
the dispensing, rotate in the first direction until powder extends
along substantially all of the tube.
8. The additive manufacturing apparatus of claim 1, wherein each
ring comprises a plurality of positions spaced angularly around the
ring, each position having one or more openings and having a
distinct combination of a number of openings and opening size.
9. The additive manufacturing apparatus of claim 8, wherein each
ring is movable between the positions such that a different
position is aligned with the at least one cap plate opening.
10. The additive manufacturing apparatus of claim 8, wherein the
combination further defines the at least one cap plate opening of
each concentric ring, the combination further comprising a number
of openings of and a position of the at least one cap plate opening
for each concentric ring.
11. The additive manufacturing apparatus of claim 1, wherein a
distal end of the powder conveyor extends over the top surface of
the platen and is closed to prevent the powder from exiting the
powder conveyor through the distal end.
12. The additive manufacturing apparatus of claim 1, wherein the at
least one cap plate opening comprises a slot extending along a
longitudinal axis of the cap plate.
13. The additive manufacturing apparatus of claim 1, wherein the at
least one cap plate opening comprises a plurality of openings for
each ring.
14. The additive manufacturing apparatus of claim 1, wherein the
tube surrounds the cap plate.
15. The additive manufacturing apparatus of claim 1, wherein the
cap plate surrounds the tube.
16. The additive manufacturing apparatus of claim 1, wherein a
drive system of each concentric ring comprises: a motor with a
rotational axis offset from and parallel to the longitudinal axis
of the powder conveyor, and a linkage system connected to the motor
such that rotation of the motor about its rotational axis causes
rotation of the concentric ring about the longitudinal axis of the
powder conveyor.
17. The additive manufacturing apparatus of claim 16, wherein the
motor of the drive system of each of the plurality of rings
comprises a distinct shaft length.
18. The additive manufacturing apparatus of claim 1, wherein a
drive system of each concentric ring comprises a solenoid
configured to generate an electromagnetic field to rotate the
concentric ring about the longitudinal axis of the powder
conveyor.
19. The additive manufacturing apparatus of claim 1, wherein: the
dispensing system is a first dispensing system, the powder is a
first powder, the additive manufacturing apparatus further
comprises a second dispensing system configured to receive a second
powder to be dispensed over the top surface of the platen, and the
second powder comprises a diameter--smaller than a diameter of the
first powder.
20. The additive manufacturing apparatus of claim 1, wherein the
energy source comprises a plurality of heaters configured to apply
the energy to the powder, the plurality of heaters being
addressable such that that the energy is selectively applied to the
powder dispensed through the at least one ring opening and the
concentric at least one cap plate opening.
21. A dispensing system comprising: a powder source configured to
hold powder to be dispensed over a top surface of a platen; an
powder conveyor extending over the top surface of the platen, the
powder conveyor comprising a proximal end configured to receive the
powder from the powder source, the powder conveyor being configured
to move the powder carried within the powder conveyor along a
length of the powder conveyor; a plurality of rings arranged
coaxially along a longitudinal axis of the powder conveyor and
forming a tube surrounding the powder conveyor and configured to
contain the powder, and each concentric ring comprising at least
one ring opening; and a cap plate extending along a length of the
tube, the cap plate comprising at least one cap plate opening
wherein each ring is configured to be independently rotatable such
that the at least one ring opening of the respective concentric
ring is movable into or out of alignment with the at least one cap
plate opening, wherein the powder is dispensed from the tube
through the at least one ring opening and the at least one cap
plate opening when the at least one ring opening and the at least
one cap plate opening are aligned.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application Ser. No. 62/262,673, filed on Dec. 3, 2015, and claims
priority to U.S. Provisional Application Ser. No. 62/219,605, filed
Sep. 16, 2015, the entirety of each being incorporated by
reference.
TECHNICAL FIELD
[0002] This specification relates to additive manufacturing, also
known as 3D printing.
BACKGROUND
[0003] Additive manufacturing (AM), also known as solid freeform
fabrication or 3D printing, refers to a manufacturing process where
three-dimensional objects are built up from successive dispensing
of raw material (e.g., powders, liquids, suspensions, or molten
solids) into two-dimensional layers. In contrast, traditional
machining techniques involve subtractive processes in which objects
are cut out from a stock material (e.g., a block of wood, plastic
or metal).
[0004] A variety of additive processes can be used in additive
manufacturing. Some methods melt or soften material to produce
layers, e.g., selective laser melting (SLM) or direct metal laser
sintering (DMLS), selective laser sintering (SLS), fused deposition
modeling (FDM), while others cure liquid materials using different
technologies, e.g., stereolithography (SLA). These processes can
differ in the way layers are formed to create the finished objects
and in the materials that are compatible for use in the
processes.
[0005] Conventional systems use an energy source for sintering or
melting a powdered material. Once all the selected locations on the
first layer are sintered or melted and then re-solidified, a new
layer of powdered material is deposited on top of the completed
layer, and the process is repeated layer by layer until the desired
object is produced.
SUMMARY
[0006] In one aspect, an additive manufacturing apparatus for
forming an object includes a platen to support the object being
formed, a dispensing system overlying the platen, and an energy
source to apply energy to the powder dispensed on the top surface
of the platen to form a fused portion of the powder. The dispensing
system includes a powder source configured to hold powder to be
dispensed over a top surface of the platen and a powder conveyor
extending over the top surface of the platen. The powder conveyor
includes a proximal end configured to receive the powder from the
powder source. The powder conveyor is configured to move the powder
carried within the powder conveyor along a length of the powder
conveyor. The dispensing system also includes rings arranged
coaxially along a longitudinal axis of the powder conveyor. The
rings form a tube surrounding the powder conveyor and are
configured to contain the powder. Each concentric ring includes at
least one ring opening. The dispensing system also includes a cap
plate extending along a length of the tube. The cap plate includes
at least one cap plate opening. Each ring is configured to be
independently rotatable such that the at least one ring opening of
the respective concentric ring is movable into or out of alignment
with the at least one cap plate opening. The powder is dispensed
from the tube through the at least one ring opening and the at
least one cap plate opening when the at least one ring opening and
the at least one cap plate opening are aligned.
[0007] Features can include one or more of the following. The
powder conveyor can be rotatable about the longitudinal axis of the
powder conveyor to move the powder carried within the powder
conveyor along the length of the powder conveyor. The powder
conveyor can further include a screw conveyor coaxial with the
longitudinal axis of the powder conveyor and rotatable about the
longitudinal axis of the powder conveyor such that, when the screw
conveyor rotates, the screw conveyor moves the powder carried
within the powder conveyor along the length of the powder
conveyor.
[0008] The screw conveyor can be configured such that when the
screw conveyor rotates in a first direction about the longitudinal
axis, the screw conveyor carries the powder along the longitudinal
axis away from the proximal end of the powder conveyor. The screw
conveyor can be further configured such that when the screw
conveyor rotates in a second direction about the longitudinal axis,
the screw conveyor carries the powder along the longitudinal axis
toward the proximal end of the powder conveyor. The additive
manufacturing apparatus can further include a motor to drive the
screw conveyor and controller coupled to the motor. The controller
can be configured to cause the screw conveyor to alternate between
the rotation in the first direction and the second direction during
dispensing of the powder to form the object. The screw conveyor can
be configured to compact the powder when the screw conveyor rotates
in the first direction. The controller can be configured to cause
the screw conveyor to, prior to the dispensing, rotate in the first
direction until powder extends along substantially all of the
tube.
[0009] Each ring can include two or more positions spaced angularly
around the ring, each position having one or more openings and
having a distinct combination of a number of openings and opening
size. Each ring can be movable between the positions such that a
different position is aligned with the at least one cap plate
opening. The combination can further define the at least one cap
plate opening of each concentric ring. The combination can further
include a number of openings of and a position of the at least one
cap plate opening for each concentric ring.
[0010] A distal end of the powder conveyor can extend over the top
surface of the platen. The distal end of the powder conveyor can be
closed to prevent the powder from exiting the powder conveyor
through the distal end. At least one cap plate opening can include
a slot extending along a longitudinal axis of the cap plate. At
least one cap plate opening can include two or more openings for
each ring. The tube can surround the cap plate, or the cap plate
can surround the tube.
[0011] A drive system of each concentric ring can include a motor
with a rotational axis offset from and parallel to the longitudinal
axis of the powder conveyor. The drive system can further include a
linkage system connected to the motor such that rotation of the
motor about its rotational axis causes rotation of the concentric
ring about the longitudinal axis of the powder conveyor. The motor
of the drive system of each of the concentric rings can include a
distinct shaft length. A drive system of each concentric ring can
include a solenoid configured to generate an electromagnetic field
to rotate the concentric ring about the longitudinal axis of the
auger conveyor.
[0012] The dispensing system can be a first dispensing system. The
powder can be a first powder. The additive manufacturing apparatus
can further include a second dispensing system configured to
receive a second powder to be dispensed over the top surface of the
platen. The second powder can include a diameter small than a
diameter of the first powder.
[0013] The energy source can include heaters configured to apply
the energy to the powder. The heater can be addressable such that
that the energy is selectively applied to the powder dispensed
through the at least one ring opening and the concentric at least
one cap plate opening.
[0014] In a further aspect, a dispensing system includes a powder
source configured to hold powder to be dispensed over a top surface
of a platen. The dispensing system further includes a powder
conveyor extending over the top surface of the platen. The powder
conveyor includes a proximal end configured to receive the powder
from the powder source. The powder conveyor is configured to move
the powder carried within the powder conveyor along a length of the
powder conveyor. The dispensing system includes rings arranged
coaxially along a longitudinal axis of the powder conveyor. The
rings form a tube surrounding the powder conveyor and configured to
contain the powder. Each concentric ring includes at least one ring
opening. The dispensing system includes a cap plate extending along
a length of the tube. The cap plate includes at least one cap plate
opening. Each ring is configured to be independently rotatable such
that the at least one ring opening of the respective concentric
ring is movable into or out of alignment with the at least one cap
plate opening. The powder is dispensed from the tube through the at
least one ring opening and the at least one cap plate opening when
the at least one ring opening and the at least one cap plate
opening are aligned.
[0015] Advantages of the foregoing may include, but are not limited
to, the following. The efficiency of forming an object and increase
overall throughput of additive manufacturing can be increased. The
dispensing system can include several paths through which powder
can be dispensed in parallel onto a platform of the additive
manufacturing apparatus. These multiple available paths can be
independently controlled such that the placement of powder onto the
build platform can be controlled.
[0016] The details of one or more implementations of the subject
matter described in this specification are set forth in the
accompanying drawings and the description below. Other potential
features, aspects, and advantages will become apparent from the
description, the drawings, and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1A is a schematic side view of an example of an
additive manufacturing apparatus.
[0018] FIG. 1B is a schematic top view of the additive
manufacturing apparatus of FIG. 1A.
[0019] FIG. 2 is a front perspective cutaway view of a
printhead.
[0020] FIG. 3A is a front-side perspective view of a dispensing
system.
[0021] FIG. 3B is a front-side perspective cross-sectional view of
the dispensing system of FIG. 3A.
[0022] FIG. 3C is an enlarged front-side perspective
cross-sectional view of the dispensing system of FIG. 3A.
[0023] FIG. 3D is a bottom view of the dispensing system of FIG.
3A.
[0024] FIG. 3E is a front view of the dispensing system of FIG.
3A.
[0025] FIG. 3F is a top view of the dispensing system of FIG.
3A.
[0026] FIG. 3G is an enlarged top cutaway view of a powder conveyor
for the dispensing system of FIG. 3A.
[0027] FIG. 4A is a bottom perspective view of a ring for a
dispensing system.
[0028] FIG. 4B is a bottom view of the ring of FIG. 4A.
[0029] FIG. 5A is a bottom perspective view of a cap plate for a
dispensing system.
[0030] FIG. 5B is a bottom view of the cap plate of FIG. 5A.
[0031] FIGS. 6A to 6F are front cross-sectional views of different
configurations of a cap plate and a ring for a dispensing
system.
[0032] Like reference numbers and designations in the various
drawings indicate like elements.
DETAILED DESCRIPTION
[0033] Additive manufacturing (AM) apparatuses can form an object
by dispensing and fusing successive layers of a powder on a build
platform. Control of the area on the build stage on which powder is
dispensed is desirable. For example, a controllable dispenser can
permit control of the geometry of the object, or simply be used to
avoid dispensing powder in areas of the build platform that will
not support the object, thus reducing the consumption of
powder.
[0034] The dispensing system described below can include
controllable and movable structures that enable the apparatus to
selectively dispense the powder on the build platform. Optionally,
the dispensing system's controllable and movable structures also
enable control of the powder dispensing rate, which can be selected
to be low for localized and precise dispensing or can be selected
to be high for high-throughput dispensing.
Additive Manufacturing Apparatuses
[0035] FIG. 1A shows a schematic side view of an example additive
manufacturing (AM) apparatus 100 that includes a dispensing system
for dispensing of powder to form an object during a build
operation. The apparatus 100 includes a printhead 102 and a build
platform 104 (e.g., a build stage). The printhead 102 dispenses a
powder 106 and, optionally, fuses the powder 106 dispensed on the
platform 104. Optionally, as described below, the printhead 102 can
also dispense and/or fuse a second powder 108 on the platform
104.
[0036] Referring to FIGS. 1A and 1B, the printhead 102 is supported
on a gantry 110 (e.g., a platform, a support) configured to
traverse the platform 104. The gantry 110 can include a
horizontally extending support on which the printheads are mounted.
For example, the gantry 110 can be driven along rails 119 by a
linear actuator and/or motor so as to move across the platform 104
along a first axis parallel to a forward direction 109. In some
implementations, the printhead 102 can move along the gantry 110
along a horizontal second axis 115 perpendicular to the first axis.
Movement along both the first and second axes enables the printhead
102 and its systems to reach different parts of the platform 104
beneath the gantry 110. The movement of the printhead 102 along the
gantry 110 and the movement of the gantry 110 along the rails 119
provide multiple degrees of freedom of mobility for the printhead
102. The printhead 102 can move along a plane above and parallel to
the build platform 104 such that the printhead 102 can be
selectively positioned above a usable area of the build platform
104 (e.g., an area where the powder can be dispensed and
fused).
[0037] The printhead 102 and the gantry 110 can cooperate to scan
the usable area of the build platform 104, enabling the printhead
102 to dispense powder along the build platform 104 as needed to
form the object. In the example as shown in FIG. 1B, the printhead
102 can scan in the forward direction 109 along the build platform
104. After the printhead 102 travels across the build platform 104
from a first end 111 to a second end 113 of the build platform 104
for a first time to deposit a first stripe of the layer of powder.
Then the printhead 102 can return to the first end 111, move in a
lateral direction along the horizontal second axis 115, and begin a
travel across the build platform 104 again in the forward direction
109 for a second time to deposit a second stripe on the build
platform 104 that is parallel to the first stripe. If the printhead
102 dispenses two or more different sizes of powder, the printhead
102 can dispense the two or more different powders during a single
pass across the platform 104.
[0038] Alternatively, the gantry 110 can include two or more
printheads that span the width of the platform 104. In this case,
motion of the printhead 102 in the lateral direction along the
horizontal second axis 115 may not be needed.
[0039] Referring to FIG. 1A and to FIG. 2, which shows a cutaway
view of the printhead 102 the printhead 102 includes at least a
first dispensing system 116 to selectively dispense powder 106 on
the build platform 104.
[0040] The apparatus 100 also includes an energy source 114 to
selectively add energy to the layer of powder on the build platform
104. The energy source 114 can be incorporated into the printhead
102, mounted on the gantry 110, or be mounted separately, e.g., on
a frame supporting the build platform 104 or on chamber wall that
surrounds the build platform 104.
[0041] In some implementations, the energy source 114 can include a
scanning laser that generates a beam of focused energy that
increases a temperature of a small area of the layer of the powder.
The energy source 114 can fuse the powder by using, for example, a
sintering process, a melting process, or other process to cause the
powder to form a solid mass of material. In some cases, the energy
source 114 can include an ion beam or an electron beam.
[0042] The energy sources 114 can be positioned on the printhead
102 such that, as the printhead 102 advances in the forward
direction 109, the energy sources can cover lines of powder
dispensed by the dispensing system 116. When the apparatus 100
includes multiple dispensing systems, the printhead 102 can also
optionally include an energy source for each of the dispensing
systems. If the apparatus includes multiple heat sources, the
energy sources can each be located immediately ahead of one of the
heat sources.
[0043] Optionally, the apparatus can include a heat source 112 to
direct heat to raise the temperature of the deposited powder. The
heat source 112 can heat the deposited powder to a temperature that
is below its sintering or melting temperature. The heat source 112
can be, for example, a heat lamp array. The energy source 114 can
be incorporated into the printhead 102, mounted on the gantry 110,
or be mounted separately, e.g., on a frame supporting the build
platform 104 or on chamber wall that surrounds the build platform
104. The heat source 112 can be located, relative to the forward
moving direction 109 of the printhead 102, behind the first
dispensing system 116. As the printhead 102 moves in the forward
direction 109, the heat source 112 moves across the area where the
first dispensing system 116 was previously located.
[0044] In some implementations, the heat source 112 is a digitally
addressable heat source in the form of an array of individually
controllable light sources. The array includes, for example,
vertical-cavity surface-emitting laser (VCSEL) chips, positioned
above the platform 104. The array can be within the printhead 102
or be separate from the printhead 102. The array of controllable
light sources can be a linear array driven by an actuator of a
drive system to scan across the platform 104. In some cases, the
array is a full two-dimensional array that selectively heats
regions of the layer by activating a subset of the individually
controllable light sources. Alternatively or in addition, the heat
source includes a lamp array to simultaneously heat the entire
layer of the powder. The lamp array can be part of the printhead
102 or can be an independent heat source unit that is part of the
apparatus 100 but separate from the printhead 102.
[0045] In some implementations, the build platform 104 may include
a heater that can heat powder dispensed on the build platform 104.
The heater can be an alternative to or in addition to the heat
source 112 of the printhead 102.
[0046] Optionally, the printhead 102 and/or the gantry 110 can also
include a first spreader 118, e.g., a roller or blade, that
cooperates with first the dispensing system 116 to compact and
spread powder dispensed by the dispensing system 116. The spreader
118 can provide the layer with a substantially uniform thickness.
In some cases, the first spreader 118 can press on the layer of
powder to compact the powder.
[0047] The printhead 102 and/or the gantry 110 can also optionally
include a first sensing system 120 and/or a second sensing system
122 to detect properties of the apparatus 100 as well as powder
dispensed by the dispensing system 116.
[0048] In some implementations, the printhead 102 includes a second
dispensing system 124 to dispense the second powder 108. A second
spreader 126 can operate with the second dispensing system 124 to
spread and compact the second powder 108. The apparatus 100, e.g.,
the printhead 102 or the gantry 110, can also include a second heat
source 125 that, like the first heat source 112, directs heat to
powder in large areas of the build platform 104.
[0049] A controller 128 can coordinate the operations of the energy
source 114, heat source 112 (if present), and dispensing system
116. The controller 128 can operate the dispensing system 116 to
dispense the powder 106 and can operate the energy source 114 and
the heat source 112 to fuse the powder 106 to form a workpiece 130
that becomes the object to be formed.
[0050] The controller 128 can operate the first dispensing system
116 to control, for example, the thickness and the distribution of
the powder 106 dispensed on the build platform 104. The thickness
of each layer depends on, for example, the number of the powder
particles 106 stacked through a height of the layer or the mean
diameter of the powder particles 106. In some implementations, each
layer of the powder particles 106 is a single particle thick. In
some cases, each layer has a thickness resulting from stacking
multiple powder particles 106 on top of each other.
[0051] In some implementations, the height of the layer also
depends on a distribution density of the powder particles 106,
e.g., how closely packed the powder particles 106 are. A level of
compaction of the powder 106 can affect the thickness of each layer
dispensed. Higher levels of compaction of the powder 106 can reduce
the thickness of the layer dispensed as compared to a layer formed
with the same number of particles at a lower level of compaction.
The higher level of compaction can further increase a uniformity of
the thickness across the layer and reduce the laser residency time
need to melt the layer. The thickness of each layer and the
compaction of the powder can be selected to control a desired
resolution for the geometry of the portion of the object being
formed in that layer.
[0052] The distribution of powder dispensed for each layer, e.g.,
the locations of the powder within each layer, can vary based on
the implementation of the additive manufacturing apparatus. In some
cases, the first dispensing system 116 can selectively dispense a
layer of powders across the build stage such that some portions
include powder and some portions do not include powder. In some
implementations, the first dispensing system 116 can dispense a
uniform layer of materials on the work surface.
[0053] Referring to FIG. 2, the first dispensing system 116
receives the powder 106 in a powder hopper 131. The powder 106 then
travels through a channel 136. The powder hopper 131 can be filled
with powder such that the powder hopper 131 serves as a powder
source for the channel 136 during a dispensing operation. The first
dispensing system 116 dispenses the powder 106 onto the build
platform 104 through one or more of several available openings or
holes extending from the channel 136. The holes or openings can be
selectively openable. In particular, the channel 136 can be formed
by selectively controllable and movable rings, e.g., rotatable
rings, that include the openings. The rings, together when stacked
along their common central cylindrical axis, can be in the shape of
a tube with the channel 136 corresponding to the aperture through
the tube. As the rings rotate, the openings move angularly around
the common cylindrical axis.
[0054] The controller 128 can selectively actuate ring drive
mechanisms 138 to control the ring through which powder is
dispensed. In cases where each ring includes multiple openings, the
controller can also actuate each of the ring drive mechanisms 138
to select one or more of the multiple openings through which to
dispense powder.
[0055] Each group of opening at a particular angular location on a
ring can be sized and dimensioned such that the powder is dispensed
at a different rate. The rotation of the rings, and hence, the
selection of the opening or openings through which the powder is
dispensed, enable the controller 128 to select a rate at which the
powder is dispensed onto the build platform 104.
[0056] Using the first dispensing system 116, the controller can
control the powder's distribution on the build platform 104 and
distribution. The first dispensing system 116 can control a
distribution of the powder in a layer dispensed on the build
platform 104 or on an uppermost layer of powder. In some cases, the
first dispensing system 116 can dispense the powder through one of
the openings to achieve selective dispensing of the powder onto the
build platform 104 or the uppermost layer of powder. In some cases,
the first dispensing system 116 can dispense the powder through
more than one opening (e.g., through a hole in each of the rings)
so that the first dispensing system 116 can dispense powder across
a larger area of the build platform 104 at once.
[0057] The first spreader 118 can then spread the powder across the
build platform 104. The spreader can provide the layer with a
substantially uniform thickness. In some implementations, the first
spreader 118 is a blade that translates across the platform 104. In
some cases, the first spreader 118 is a roller or rotating cylinder
that rolls across the platform 104. The spreader 118 can roll in a
clockwise direction and/or a counterclockwise direction.
[0058] Optionally, the printhead can include a second dispensing
system 124 to deliver a second powder. The second dispensing system
124 receives the powder 108 in a powder hopper 134. The powder 108
then travels through a channel 136. Similar to the first dispensing
system 116, the second dispensing system 124 can control the rate
at which powder is dispensed through the build platform 104 by
rotating rings containing holes through which the powder is
dispensed. The second dispensing system 124 can also compact the
powder so that powder dispensed from the first dispensing system
116 has a desired distribution density.
[0059] If present, the second dispensing system 124 enables
delivery a second type of powder 108 having properties different
than the first powder 106. The first powder particles 106 can have
a larger mean diameter than the second particle particles 108,
e.g., by a factor of two or more. When the second powder particles
108 are dispensed on a layer of the first powder particles 106, the
second powder particles 108 infiltrate the layer of first powder
particles 106 to fill voids between the first powder particles 106.
The second powder particles 108, being smaller than the first
powder particles 106, can achieve a higher resolution, higher
pre-sintering density, and/or a higher compaction rate.
[0060] Alternatively or in addition, if the apparatus 100 includes
two types of powders, the first powder particles 106 can have a
different sintering temperature than the second particle particles.
For example, the first powder can have a lower sintering
temperature than the second powder. In such implementations, the
energy source 114 can be used to heat the entire layer of powder to
a temperature such that the first particles fuse but the second
powder does not fuse.
[0061] In some implementations, the controller 128 can control the
first and second dispensing systems 116, 124 to selectively deliver
the first and the second powder particles 106, 108 to different
regions.
[0062] In implementations when multiples types of powders are used,
the first and second dispensing systems 116, 124 can deliver the
first and the second powder particles 106, 108 each into selected
areas, depending on the resolution requirement of the portion of
the object to be formed.
[0063] Materials for the powder include metals, such as, for
example, steel, aluminum, cobalt, chrome, and titanium, alloy
mixtures, ceramics, composites, and green sand. In implementations
with two different types of powders, in some cases, the first and
second powder particles 106, 108 can be formed of different
materials, while, in other cases, the first and second powder
particles 106, 108 have the same material composition. In an
example in which the apparatus 100 is operated to form a metal
object and dispenses two types of powder, the first and second
powder particles 106, 108 can have compositions that combine to
form a metal alloy or intermetallic material.
[0064] If the apparatus 100 dispenses two different types of
powders having different sintering temperatures, the first and
second heat sources 112, 125 can have different temperature or
heating set points. For example, if the first powder 106 can be
sintered at a lower temperature than the second powder 108, the
first heat source 112 may have a lower temperature set point than
the second heat source 125.
[0065] In some implementations, the building platform 104 is fixed
and the printhead 102 moves in a vertical direction to dispense
successive layers of the powder. In some implementations, the build
platform 104 can be moved upward or downward during build
operations. For example, the build platform 104 can be moved
downward with each layer dispensed by the first dispensing system
116 so that the printhead 102 can remain at the same vertical
height with each successive layer dispensed. The controller 128 can
operate a drive mechanism, e.g., a piston or linear actuator,
connected to the build platform 104 to decrease a height of the
build platform 104 so that the build platform 104 can be moved away
from the printhead 102. Alternatively, the build platform 104 can
be held in a fixed vertical position, and the gantry 110 can be
raised after each layer is deposited.
[0066] The controller 128 controls the operations of the apparatus
100, including the operations of the printhead 102 and its
subsystems, such as the heat source 112, the energy source 114, and
the first dispensing system 116. The controller 128 can also
control, if present, the first spreader 118, the first sensing
system 120, the second sensing system 122, the second dispensing
system 124, and the second spreader 126. The controller 128 can
also receive signals from, for example, user input on a user
interface of the apparatus or sensing signals from sensors of the
apparatus 100.
[0067] The controller 128 can include a computer aided design (CAD)
system that receives and/or generates CAD data. The CAD data is
indicative of the object to be formed, and, as described herein,
can be used to determine properties of the structures formed during
additive manufacturing processes. Based on the CAD data, the
controller 128 can generate instructions usable by each of the
systems operable with the controller 128, for example, to dispense
the powder 106, to fuse the powder 106, to move various systems of
the apparatus 100, and to sense properties of the systems, powder,
and/or the workpiece 130.
[0068] The controller 128, for example, can transmit control
signals to drive mechanisms that move various components of the
apparatus. In some implementations, the drive mechanisms can cause
translation and/or rotation of these different systems, including
dispensers, rollers, support plates, energy sources, heat sources,
sensing systems, sensors, dispenser assemblies, dispensers, and
other components of the apparatus 100. Each of the drive mechanisms
can include one or more actuators, linkages, and other mechanical
or electromechanical parts to enable movement of the components of
the apparatus.
[0069] The controller 128, in some cases, controls movement of the
printhead 102 and can also control movements of individual systems
of the printhead 102. For example, the controller 128 can cause the
printhead 102 to move to a particular location along the gantry
110, and the controller 128 can transmit a separate control signal
to drive a separate drive mechanism to move the energy source 114
of the printhead 102 along the printhead 102. The apparatus 100 can
further include a drive mechanism that moves the gantry 110 along
the build platform 104 so that the printhead 102 can be positioned
above different areas of the build platform 104.
[0070] The controller 128 can also control individual structures of
the dispensing system 116, including the movable and controllable
rings described herein and a powder conveyor contained within the
dispensing system 116. The controller 128 can control the
dispensing system 116 to adjust delivery rates of the powder, a
level of compaction of the powder, as well as the locations on the
build platform 104 where the powder is dispensed.
Dispensing Systems
[0071] FIGS. 3A to 3G depict various views of the dispensing system
116 (and/or, e.g., the second dispensing system 124). As shown in
the perspective view of the dispensing system 116 shown in FIG. 3A,
the dispensing system 116 includes the powder hopper 131 to receive
powder to be dispensed (and possibly compacted) by the dispensing
system 116.
[0072] Also referring to FIG. 3B depicting a perspective
cross-sectional view of the dispensing system 116, powder travels
through the powder hopper 131 into the channel 136. A conveyor
drive mechanism 139 of the dispensing system 116 can drive a powder
conveyor 140 that causes the powder to move between an entrance 142
of the channel 136 and a closed end 144 of the channel 136. The
powder conveyor 140 can be an auger screw.
[0073] The conveyor 140 can rotate to carry the powder within the
channel 136. For example, rotation of an augur screw can drive
powder forward through the channel 136.
[0074] In some implementations, the conveyor 140, instead of
rotating, translates along the channel 136 to distribute the powder
within the channel 136. In some implementations, the conveyor 140
oscillates or vibrates to distribute the powder within the channel
136.
[0075] In some implementations, the conveyor drive mechanism 139
can include a drive motor 141. The drive motor 141 can be a high
torque drive motor that enables the conveyor drive mechanism 139 to
cause the conveyor 140 to exert high levels of pressure on powder
within the channel 136. In some implementations, the drive
mechanism 139 can further include gears, linkages, and other force
and torque transfer devices that transfer the torque from the drive
motor to the conveyor 140.
[0076] Referring to FIG. 3C, which shows an enlarged perspective
cross-sectional view of the channel 136 of the dispensing system
116. A series of annular rings 146 encircle the conveyor 140. The
apertures through the rings 146 define the channel 136 through
which the powder travels. In particular, an inside surface of the
rings 146 form the channel 136. Thus, as powder is travelling
through the channel 136, the powder contacts the inside surface of
the rings 146. The annular rings 146 each have a center that is
concentric with a longitudinal axis 162 of the conveyor 140. In
some implementations, the conveyor 140 rotates about this
longitudinal axis 162 to move the powder through the channel
136.
[0077] As shown in FIGS. 4A and 4B, which are a bottom perspective
view and a bottom view, respectively, of an example of the ring
146, each of the rings 146 includes an opening 148 that goes
through the ring 146 from the inside surface to an outside surface
of the ring 146.
[0078] In some implementations, each of the rings 146 includes
multiple openings 148 spaced at different angular positions around
the ring 146. The openings 148 can vary in size, shape, and
quantity. For example, each of the rings 146 can include multiple
openings of different sizes. In some cases, one or more of
different angular positions on the ring 146 can include multiple
openings. While three openings 148 are shown in FIGS. 4A and 4B, in
some cases, a ring 146 could have just two, or four or more
openings, each having a different size. Each ring can have the same
pattern of openings. In some cases, the rings 146 each have a
single opening 148 of the same size. For circular openings 148, the
diameter of the openings 148 can be between, for example, 10
micrometers and 100 micrometers.
[0079] Also referring to FIG. 3D, showing a bottom view of the
dispensing system 116, a cap plate 150 is positioned beneath the
rings 146. The cap plate 150 extends along the channel 136 and
extends along a combined length of the portion of the channel 136
provided by the rings 146. The cap plate includes openings 152.
Each of the openings 152 of the cap plate 150 can correspond a
different one of the rings 146. The openings can be arranged on
line parallel to the longitudinal axis.
[0080] Each opening 152 can be larger or smaller than the opening
148 of the corresponding ring 146. In some cases, as shown in FIGS.
5A and 5B, which show a bottom perspective view and a bottom view
of an example of the cap plate 150, all of the openings 152 can
have the same size. The openings 152 can be aligned with one
another and evenly spaced apart.
[0081] While described as circular openings, the openings 148 and
the openings 152 can be slots, slits, or other appropriate shapes.
In some cases, the openings 148 and/or the openings 152 can be
rectangular or oval. Although the cap plate 150 has been described
to include several cap plate openings 152 with at least one cap
plate opening for each ring 146, in some cases, the cap plate 150
includes a single slot that extends beneath all or several of the
rings. The slot can extend parallel to the longitudinal axis of the
channel. For example, the cap plate 150 could include two or more
slots, each slot corresponding to two or more of the rings. In some
cases, the cap plate includes one slot extending across all of the
rings. In some implementations, the slot has a uniform width, while
in other cases, the slots vary in width.
[0082] The rings 146 are adjacent to and above the cap plate 150,
so the openings 148 of the rings 146 can be aligned with the
openings 152 of the cap plate 150. In particular, each ring 146 can
be rotated such that its opening 148 can align with its
corresponding opening in the cap plate 150. FIG. 3E shows a front
cross-sectional view of the dispensing system 116, and FIG. 3F
shows a top cross-sectional view of the dispensing system 116. The
dispensing system 116 includes ring drive mechanisms 138, each of
which are connected to a corresponding one of the rings 146.
[0083] In some implementations, each of the ring drive mechanisms
138 can include a motor 156 and a linkage system 158 such that the
motor can cause one of the rings 146 to rotate. The linkage system
158 can include gears, linkages, arms, and other force and torque
transmitting elements to transfer the torque of the motor 156 into
a rotational force on its associated ring 146. The motor 156 can be
operated to rotate its associated ring 146 in both directions about
its center. In some implementations, shaft lengths of the motors
156 can vary such that the motors 156 can each be mounted onto the
same planar surface. In some implementations, each of the ring
drive mechanisms 138 or each of the motors 156 can operate two or
more of the rings 146 to rotate two or more of the rings
simultaneously.
[0084] The ring drive mechanisms 138 rotate the rings 146 about the
centers of the rings 146. The center of the rings 146 can coincide
with the longitudinal axis 162 of the conveyor 140. Thus, as the
rings 146 rotate, the channel 136 formed by the rings 146 can
remain substantially the shape and size.
[0085] In some implementations, the rings are driven by a magnetic
drive mechanism. The magnetic drive mechanism can rotate the rings.
In some cases, the magnetic drive mechanism closes or opens an
opening of the ring depending on a polarity of the magnetic drive
mechanism. The magnetic drive mechanism can include a solenoid. The
controller can control the solenoid to generate an electromagnetic
field that interacts with magnetic or ferromagnetic material of one
of the rings 146. The electromagnetic field can drive the ring 146
about the longitudinal axis 162 of the conveyor 140.
[0086] For each ring 146, the controller (e.g., the controller 128
of the apparatus 100 shown in FIG. 1B) can control the
corresponding ring drive mechanism 138 of the ring 146 to set a
rotational position of the ring 146. The rotational position of the
ring 146 determines the position of the opening 148 of the ring 146
relative to the corresponding opening 152 of the cap plate 150. In
the examples shown and described with respect to FIGS. 4A, 4B, 5A,
and 5B, each ring 146 has multiple openings 148 and has one
corresponding opening 152 in the cap plate 150.
[0087] The controller can operate one of the ring drive mechanisms
138 to dispense powder from the ring 146 associated with that ring
drive mechanism 138. The controller can operate the ring drive
mechanism 138 to rotate the ring 146 such that one of the openings
148 of the ring 146 aligns with its corresponding opening 152 in
the cap plate 150. When the opening 148 is aligned with the
corresponding opening 152, powder travelling through the channel
136 formed by the set of rings 146 can travel through the opening
148 and the corresponding opening 152. That powder can therefore
travel through the cap plate 150 and can be dispensed onto the
build platform (e.g., the build platform 104 of the apparatus 100
shown in FIGS. 1A and 1B).
[0088] The controller can also operate the ring drive mechanism 138
so that powder is not dispensed from the associated ring 146. The
controller can also operate the ring drive mechanism 138 to rotate
the ring 146 such that the openings 148 of the ring 146 are
misaligned with their corresponding opening in the cap plate 150.
When the openings 148 and 152 are misaligned, powder in the channel
136 is blocked by the body of the cap plate 150 and unable to pass
through the ring 146, as their respective openings 148, 152 do not
provide a path for the powder. The powder therefore is not
dispensed from the portion of the channel 136 corresponding to that
ring 146.
[0089] In cases where the ring 146 includes multiple openings 148
at different angular positions around the ring, the controller can
select one of the openings 148 from among the several openings to
align to the respective opening 152 control a rate of the powder
dispensed from the channel 136 through the ring 146. If the
multiple openings 148 have different sizes as shown in FIGS. 4A and
4B, the larger sized openings can dispense powder at a greater rate
than the smaller sized openings. Similarly, the smaller sized
openings can dispense powder at a lower rate than the larger sized
openings. To control the powder dispensing rate from the channel
136, the controller can select which of the openings 148, among the
larger and smaller multiple openings 148, to align with the
corresponding openings 152 of the cap plate 150.
[0090] In some implementations, the controller can cause partial
alignment of the opening 148 and the corresponding opening 152 in
the cap plate 150 to control the powder dispensing rate. In cases
where the ring 146 has multiple openings 148, the controller can
operate the ring drive mechanism 138 so that one of the openings
148 and the corresponding opening 152 in the cap plate 150 are in a
partially aligned positions relative to one another. In the
partially aligned positions, the opening 148 of the ring 146 and
the opening 152 of the cap plate enable powder to be dispensed from
the portion of the channel 136. However, the partial alignment can
reduce the rate of powder dispensed from that portion of the
channel 136 as compared to the rate of powder dispensed from that
portion if the opening 148 and the corresponding opening 152 were
in full alignment. Although the ring 146, for example as shown in
FIGS. 4A and 4B, has three openings 148, the controller can select
from more than three powder dispensing rates by partially aligning
the openings 148 with the opening 152 in the cap plate.
[0091] In some implementations, the ring 146 may only have a single
opening 148. In some implementations, even though the ring 146 only
has a single opening, the controller can still modulate the powder
dispensing rate by controlling an amount of alignment between the
single opening 148 and the opening 152 of the cap plate 150. In
some implementations in which the ring 146 has only a single
opening, the controller is configured to simply provide a binary
on/off state for dispensing of the powder.
[0092] The controller can also control the rotational position of
each of the rings 146 for simultaneous dispensing powder from
multiple rings 146. In particular, the controller can select
multiple rings, and therefore multiple locations along the channel
136, from which the powder is dispensed. In some cases, the
controller can dispense large amounts of powder across a wide area.
In this regard, the controller can rotate several or all of the
rings 146 such that their openings 148 are fully aligned with their
corresponding openings 152. In this configuration, the controller
can dispense powder from each of the openings 152 of the cap plate
150, thus enabling the dispensing system 116 to dispense large
amounts of powder across a wide area.
[0093] In some cases, the controller can dispense a small amount of
powder in a localized or limited area by dispensing powder from a
subset of the rings 146. The controller can control the subset of
the rings 146 so that their openings 148 are aligned with their
corresponding openings 152 in the cap plate 150. For the remaining
rings 146, the controller can control them such that their openings
148 are misaligned with the corresponding openings 152 in the cap
plate 150. In this configuration, the dispensing system 116
dispenses powder only through those rings 146 who are in the
positions in which their openings 148 are aligned with the
corresponding openings 152 in the cap plate 150.
[0094] The conveyor 140, which moves the powder to be dispensed
through the openings 152, can be an auger conveyor or screw
conveyor with helical blades 160. The helical blades 160 can be
helical screw blades. As the threads push the powder, the powder
can travel along the channel 136. The helical blades 160 can rotate
about a longitudinal axis 162 of the auger conveyor, which can be
coincident with the centers of the rings 146. The conveyor drive
mechanism 139 can provide the torque to rotate the auger conveyor.
As the auger conveyor rotates, the helical blades 160 push the
powder contained in the channel 136 so that the powder can travel
through the channel 136. The auger conveyor can move the powder
along the length of the auger conveyor. In this regard, the auger
conveyor can move the powder and enable the powder to be dispensed
from the different portions of the channel 136 along the length of
the channel 136. These different portions can correspond to the
different ring openings 148 and the different cap plate openings
152. In some implementations, the auger conveyor includes a lead
screw in which the threads serve as the pushing surface for the
powder.
[0095] The powder can be moved in both directions along the
longitudinal axis 162 of the conveyor 140. For example, during a
dispensing operation, the controller can control the auger conveyor
to alternate directions of rotation. This back and forth motion can
be more effective in dispensing the powder.
[0096] The controller, in some cases, can control the conveyor 140
to compact the powder before the powder is dispensed from the
channel 136 onto the build platform. In some implementations, as
shown in FIG. 3G, the end 144 of the conveyor 140 can be closed.
When the channel 136 is filled with powder, the conveyor 140 can
push the powder toward the end 144 without causing bulk movement of
the powder. Rather, because the channel 136 is filled with the
powder, the conveyor 140 can cause compaction of the powder.
[0097] While FIGS. 4A and 4B depict multiple ring openings 148 of
varying sizes for a particular example of a ring 146 and FIGS. 5A
and 5B depict one cap plate opening 152 for each ring 146, in other
implementations, the combination of the number of ring openings,
the number of corresponding cap plate openings per ring, the size
of the ring openings, and the size of the cap plate openings may
vary. While FIGS. 5A and 5B depict a uniform cap plate opening 152
for each ring 146, in some implementations, the cap plate opening
or openings for each ring can vary in size and quantity from one
another. For example, a set of cap plate openings for a single ring
can include two or more cap plate openings while another set of cap
plate openings for a single ring can include only a single cap
plate opening.
[0098] FIGS. 6A to 6F show front cross-sectional views taken along
a section line passing through a ring opening or ring openings and
a cap plate opening or cap plate openings. These views thus depict
the ring openings or openings for a particular ring 146 and the
corresponding cap plate opening or openings in the cap plate 150
for that ring. The ring 146 rotates relative to the cap plate 150
about the longitudinal axis 162, e.g., the ring 146 rotates while
the cap plate 150 remains stationary relative to the dispenser (the
entire dispenser can be moving laterally across the build
platform). As described in greater detail below, the rotation of
the ring 146 enables powder to be dispensed from the portion of the
channel 136 formed by the ring 146. Only one ring 146 is shown in
each of these views, but the channel 136 is defined by a series of
rings that may have ring openings of varying size and quantity.
[0099] In some implementations, the multiple ring openings 148 of a
particular ring 146 are all smaller than the corresponding cap
plate opening 152. The size of the ring openings 148 can thus
determine the powder dispensing rate from the ring 146. In some
cases, as shown in FIG. 6A, some of the ring openings of a ring 146
are smaller than the corresponding cap plate opening, while some of
the ring openings of the ring 146 are larger than the corresponding
cap plate opening 152. In particular, ring openings 600A and 605A
are smaller than the cap plate opening 615A, and the ring opening
610A is larger than the cap plate opening 615A. When either the
ring opening 600A or the ring opening 605A is aligned with the cap
plate opening 615A, the powder dispensing rate can be proportional
to a size of the ring openings 600A, 600B (e.g., an area of the
openings 600A, 600B). In contrast, when the ring opening 610A is
aligned with the cap plate opening 615A, because the cap plate
opening 615A is smaller than the ring opening 610A, the powder
dispensing rate is based on a size of the cap plate opening 615A.
The cap plate opening 615A can thus determine an upper limit for a
powder dispensing rate.
[0100] In some implementations, as shown in FIG. 6B, the number of
ring openings can be more than three. For example, the ring 146 can
have five ring openings, in particular, the ring openings 600B,
605B, 610B, 615B, 620B. The ring openings each have a different
size. FIG. 6B depicts the ring openings 600B, 605B, 610B, 615B as
being smaller than the cap plate opening 625B in the cap plate 150.
And, the ring opening 620B is larger than the cap plate opening
625B. In this example, while the cap plate opening 625B is smaller
than the largest ring opening 620B, for other rings in the
dispensing system, the largest ring opening may be smaller than the
cap plate opening. For other rings in the dispensing system, one,
two, three, four, or all of the ring openings may be smaller than
the cap plate opening.
[0101] While the examples described with respect to FIGS. 3A to 3G
indicate that the controller controls one ring opening to align,
misalign, or partially align with one cap plate opening, in some
cases, the controller can control a ring opening to align with two
or more cap plate openings. As shown in FIG. 6C, the ring 146 has
three ring openings 600C, 605C, 610C, and the cap plate 150 has a
set 615C of five cap plate openings. Each of the cap plate openings
can have the same size.
[0102] When the ring opening 605C is aligned with the set 615C of
the cap plate openings to dispense powder as shown in FIG. 6C, the
ring opening 605C can align with three of the cap plate openings of
the set 615C. When the ring opening 600C is aligned with the cap
plate openings, the ring opening 600C can align with one of the cap
plate openings of the set 615C. When the ring opening 610C is
aligned with the cap plate openings, the ring opening 610C can
align with five of the cap plate openings of the set 615C. The
controller can thus control the powder dispensing rate from ring
146 based on the number of cap plate openings aligned with one of
the ring openings.
[0103] In some cases, the ring 146 only has one opening that can
align with all available cap plate openings of the set 615C. For
example, the ring 146 could have only the largest ring opening
610C. Rather than partially aligning the ring 146 with a single
opening as described with respect to FIGS. 3A to 3G, the controller
can control the ring 146 to align the ring opening 610C with one or
more of the cap plate openings of the set 615C. The controller can
select the number of cap plate openings aligned with the ring
opening 610C to control the powder dispensing rate through the ring
146.
[0104] In some implementations, instead of ring openings of varying
size within a single ring, the ring 146 could have ring openings of
the same size. As shown in FIG. 6D, the ring openings can be
arranged into multiple sets 600D, 605D, and 610D of ring openings.
Each one of the sets can be aligned with the cap plate opening
615D. In the example depicted in FIG. 6D, each of the sets 600D,
605D, 610D have ring openings spaced apart and sized such that
alignment with the cap plate opening 615D enables all of the ring
openings to be dispense powder through the cap plate opening 615D.
To control a powder dispensing rate, the controller can control
which of the sets 600D, 605D, 610D to align with the cap plate
opening 615D. In some implementations, some of the ring openings
within a set can be blocked by the cap plate 150.
[0105] While the ring 146 has been described to be contained within
or above the cap plate 150 or the cap plate 150 has been described
to encircle the ring 146, in some implementations, the ring 146 can
surround the cap plate 150. In some cases, the cap plate 150,
rather than being a half-tube, the cap plate is a plate with cap
plate openings or a beam with cap plate openings. In some
implementations, the cap plate 150 is a full tube that is encircled
by the series of rings 146. For example, as shown in FIG. 6E, the
cap plate 150 is a full tube encircled by the rotating ring 146.
The cap plate includes a set 600E of cap plate openings, and the
ring 146 includes three ring openings 605E, 610E, 615E. In contrast
to the examples described with respect to FIGS. 3A to 3G and
elsewhere, in the example of FIG. 6E, when the ring openings 605E,
610E, 615E are misaligned with the set 600E of cap plate openings,
the ring 146 blocks the powder from being dispensed from the
channel 136.
[0106] In another example, as shown in FIG. 6F, the ring 146 has a
single opening 600F and the cap plate 150 has a single opening
605F. The ring 146 also encircles the cap plate 150. The controller
can control the amount of the ring opening 600F aligned with the
cap plate opening 605F to control a powder dispensing rate from the
ring 146.
[0107] These different examples depicted in and described with
respect to FIGS. 6A to 6F, while not limiting to the scope of the
number of combinations possible with regards to opening size and
quantity, illustrate examples of combinations different sizes and
quantities of ring openings and cap plate openings.
[0108] The dispensing systems described herein (e.g., the first
dispensing system 116 of FIGS. 1A and 1B) can be operated to
provide parallel dispensing of the powder through multiple holes
The dispensing system can also selectively dispense through a
subset of the holes to dispense powder in a localized area within a
layer. The selective dispensing of the powder can enable the
additive manufacturing apparatus to reduce powder use in cases
where the object to be formed does not span the entire build
platform. By having individual control of the holes, the dispensing
system can rapidly dispense layers of the powder while still
achieving selective dispensing.
Operations of the Dispensing Systems
[0109] The dispensing systems described herein facilitate
dispensing and compaction of powder onto the build platform of the
apparatus. Referring to FIG. 1A, 1B, the controller 128 can operate
the apparatus 100, and in particular, the dispensing system 116 to
control the dispensing and compacting operations. The controller
128 can receive signals from, for example, user input on a user
interface of the apparatus or sensing signals from sensors of the
apparatus 100. The user input can CAD data indicative of the object
to be formed. The controller 128 can use that CAD data to determine
properties of the structures formed during additive manufacturing
processes. Based on the CAD data, the controller 128 can generate
instructions usable by each of the systems operable with the
controller 128, for example, to dispense the powder, to fuse the
powder, to move various systems of the apparatus 100, and to sense
properties of the systems, powder, and/or the workpiece 130.
[0110] In an example process of dispensing and compacting the
powder, referring to FIG. 3A, powder particles are first loaded
through the powder hopper 131. Referring to FIG. 3B, the powder
particles travel through the powder hopper 131 toward the entrance
142 of the channel 136. The powder hopper 131 can be a reservoir
for the powder. During the dispensing operations, the powder hopper
131 thereby serves as a powder source for the powder conveyor 140
and the channel 136.
[0111] The controller of the apparatus can control the conveyor
drive mechanism 139 to drive the powder conveyor 140. As the powder
conveyor 140 is driving, the powder particles at the entrance 142
are conveyed toward the closed end 144. The powder conveyor 140 can
continue conveying the powder until the powder particles
substantially fill the channel 136.
[0112] In some implementations, the controller can determine that
the powder particles have substantially filled the channel 136. For
example, the controller can operate the conveyor drive mechanism
139 in a speed control mode and can determine that a power level
exceeding a certain threshold is indicative of the powder particles
having filled the channel 136. The controller, upon determining
that the powder particles have filled the channel 136, can control
an amount of compaction based on the power level at which the
conveyor drive mechanism 139 is operated. In some cases, the
channel 136 can include optical sensors, force sensors, or other
appropriate sensors that can detect an amount of packing of the
powder particles, which can in turn indicate the amount of
compaction of the powder particles. The pre-compaction of powder
can enable greater uniformity of powder dispensed within and
between each successive layer dispensed onto the build platform by
the dispensing system 116.
[0113] The rings 146, before the controller operates the ring drive
mechanisms 138, can initially each be set such that their openings
148 are in misaligned positions relative to the openings 152 of the
cap plate 150. In this configuration, powder cannot be dispensed
form any of the rings 146. When the controller has determined that
the powder particles have substantially filed the channel 136
and/or has compacted the powder particles to a desired level of
compaction, the controller can operate the ring drive mechanisms
138, as shown in FIGS. 3C, 3D, and 3E, to rotate the rings 146. In
particular, the controller can change rotational positions of the
rings 146 relative to the cap plate 150 to control a powder
dispensing rate from each of the rings 146.
[0114] Each ring 146 and its corresponding cap plate openings or
opening can have a configuration of ring openings and cap plate
openings, for example, one of configurations described in examples
of FIGS. 6A to 6D. The rings 146 and its cap plate opening or
openings may each a configuration that differs from the
configuration of the other rings and cap plate openings. The
controller can rotate the rings 146 to change the alignment of the
ring openings and the cap plate openings.
[0115] The controller, based on, for example, stored data on each
of the configurations of the rings 146 and the cap plate openings
152, can set a powder dispensing rate from each of the rings 146.
The stored data can include information pertaining to, for example,
sizes, positions, and other geometry of the openings 148 of each of
the rings 146 and the openings 152 of the cap plate. Based on the
geometric characteristics of the openings 148, 152 and the torque
provided by the powder conveyor 140, the controller can compute an
expected delivery rate of the powder from the combination of a
particular opening of the rings 146 aligned with a particular
opening of the cap plate 150.
[0116] This control of the rotational position of the rings enables
the controller to set the powder dispensing rate as well as the
locations along the channel 136 where powder is to be dispensed.
The controller can control the rings 146 such that powder is
dispensed from all of the rings 146, thus enabling wide parallel
dispensing of powder onto the build platform of the apparatus. The
controller can also control the rings 146 such that powder is only
dispensed from some of the rings 146. The controller can therefore
localize the powder dispensing to occur only along a portion of the
channel 136.
[0117] The controller can control the level of compaction, the
location of powder dispensing, and the rate of powder dispensing
based on the desired levels for each of those parameters included
in the CAD data. In this regard, the controller can control the
ring drive mechanisms 138 and the conveyor drive mechanism 139 to
achieve these desired parameters. Furthermore, the controller can
use the CAD data, which can specify the geometry of the object to
be formed, to control where the powder is to be dispensed. While
the controller can control a position of the dispensing system
above the build platform to control where the powder is dispensed,
the controller can also control where along the dispensing system
the powder is dispensed.
[0118] Referring to FIGS. 1A and 1B, the controller can control
other systems to perform operations to form the object. These
systems include the printhead 102, the heat source 112, and the
energy source 114 to fuse the powder dispensed by the dispensing
system 116. After the dispensing system 116 has dispensed a layer
of the powder, the controller can control the heat source 112 and
the energy source 114 to cooperate to heat and fuse the powder
within the layer. The controller can then control the dispensing
system 116 to dispense another layer of the powder.
[0119] Controllers and computing devices can implement these
operations and other processes and operations described herein. As
described above, the controller 128 of the apparatus 100 can
include one or more processing devices connected to the various
components of the apparatus 100, e.g., actuators, valves, and
voltage sources, to generate control signals for those components.
The controller can coordinate the operation and cause the apparatus
100 to carry out the various functional operations or sequence of
steps described above. The controller can control the movement and
operations of the systems of the printhead 102. The controller 128,
for example, controls the location of feed material, including the
first and second powder particles. The controller 128 also controls
the intensity of the energy source based on the number of layers in
a group of layers to be fused at once. The controller 128 also
controls the location where energy is added by, for example, moving
the energy source or the printhead.
[0120] The controller 128 and other computing devices part of
systems described herein can be implemented in digital electronic
circuitry, or in computer software, firmware, or hardware. For
example, the controller can include a processor to execute a
computer program as stored in a computer program product, e.g., in
a non-transitory machine readable storage medium. Such a computer
program (also known as a program, software, software application,
or code) can be written in any form of programming language,
including compiled or interpreted languages, and it can be deployed
in any form, including as a standalone program or as a module,
component, subroutine, or other unit suitable for use in a
computing environment.
[0121] The controller 128 and other computing devices part of
systems described can include non-transitory computer readable
medium to store a data object, e.g., a computer aided design
(CAD)-compatible file that identifies the pattern in which the feed
material should be deposited for each layer. For example, the data
object could be a STL-formatted file, a 3D Manufacturing Format
(3MF) file, or an Additive Manufacturing File Format (AMF) file.
For example, the controller could receive the data object from a
remote computer. A processor in the controller 128, e.g., as
controlled by firmware or software, can interpret the data object
received from the computer to generate the set of signals necessary
to control the components of the apparatus 100 to fuse the
specified pattern for each layer.
[0122] While this document contains many specific implementation
details, these should not be construed as limitations on the scope
of any inventions or of what may be claimed, but rather as
descriptions of features specific to particular embodiments of
particular inventions. Certain features that are described in this
document in the context of separate embodiments can also be
implemented in combination in a single embodiment. Conversely,
various features that are described in the context of a single
embodiment can also be implemented in multiple embodiments
separately or in any suitable subcombination. Moreover, although
features may be described above as acting in certain combinations
and even initially claimed as such, one or more features from a
claimed combination can in some cases be excised from the
combination, and the claimed combination may be directed to a
subcombination or variation of a subcombination.
[0123] The printhead of FIG. 1A includes several systems that
enable the apparatus 100 to build objects. In some cases, instead
of a printhead, an AM apparatus includes independently operated
systems, including independently operated energy sources,
dispensers, and sensors. Each of these systems can be independently
moved and may or may not be part of a modular printhead. In some
examples, the printhead includes only the dispensers, and the
apparatus include separate energy sources to perform the fusing
operations. The printhead in these examples would therefore
cooperate with the controller to perform the dispensing
operations.
[0124] While the operations are described to include a single size
of powder particles, in some implementations, these operations can
be implemented with multiple different sizes of powder particles.
While some implementations of the AM apparatus described herein
include two types of particles (e.g., the first and the second
powder particles), in some cases, additional types of particles can
be used. As described above, the first powder particles have a
larger size than the second powder particles. In some
implementations, prior to dispensing the second powder particles to
form a layer, the apparatus dispenses third powder particles onto
the platen or underlying previously dispensed layer.
[0125] The processing conditions for additive manufacturing of
metals and ceramics are significantly different than those for
plastics. For example, in general, metals and ceramics require
significantly higher processing temperatures. Thus 3D printing
techniques for plastic may not be applicable to metal or ceramic
processing and equipment may not be equivalent. However, some
techniques described here could be applicable to polymer powders,
e.g. nylon, ABS, polyetheretherketone (PEEK), polyetherketoneketone
(PEKK) and polystyrene.
[0126] A number of implementations have been described.
Nevertheless, it will be understood that various modifications may
be made. For example, [0127] Various components described above as
being part of the printhead, such as the dispensing system(s),
spreader(s), sensing system(s), heat source and/or energy source,
can be mounted on the gantry instead of in the printhead, or be
mounted on the frame that supports the gantry. [0128] The
dispensing system(s) can each include two or more powder conveyors,
e.g., two or more screw conveyors or auger conveyors. [0129] The
cap plate can include a drive mechanism that rotates the cap plate
relative to the rings. In some cases, the cap plate can translate
relative to the rings. Movement of the cap plate relative to the
rings can further facilitate alignment and misalignment of the
openings of the rings and the openings of the cap plate. [0130] The
cap plate can include nozzles for each of the cap plate openings
that enable a more precise delivery of the powder onto the build
platform.
[0131] Accordingly, other implementations are within the scope of
the claims.
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